Method of making polybenzimidazole

ABSTRACT

A method of making a polybenzimidazole (PBI) includes the steps of: reacting, in a solution, an organic compound having at least 2 amino groups with an organic aldehyde adduct, the reactants comprise at least 8% by weight of the solution. A solvent of the solution may be selected from the group of: N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), tetramethylene sulfone, and combinations thereof. The organic aldehyde adduct may be an organic aldehyde bisulfite adduct. The organic aldehyde portion of the organic aldehyde adduct being aliphatic, alicyclic, aromatic, heterocyclic, or heteroaromatic aldehyde or mixtures thereof. The polybenzimidazole may have an intrinsic viscosity of at least 0.40 dl/g.

RELATED APPLICATIONS

This application claims is a divisional application claiming the benefitof co-pending U.S. patent application Ser. No. 14/293,211 filed Jun. 2,2014, now U.S. Pat. No. ______ which claimed the benefit of U.S.provisional patent application Ser. No. 61/830,869 filed Jun. 4, 2013,both incorporated herein by reference.

FIELD OF THE INVENTION

The instant invention is directed to a process for makingpolybenzimidazole.

BACKGROUND OF THE INVENTION

Polybenzimidazoles (PBI) are a known class of compounds, see thediscussion below. Also see: Powers, E. J. and Serad, G. A., History andDevelopment of Polybenzimidazole, Symposium on the History of HighPerformance Polymers, American Chemical Society (1986). PBI may be madeby either a melt/solid polymerization or a solution polymerization. Todate, the most prominent commercial process for the manufacture of PBIhas been the melt/solid polymerization.

The melt/solid polymerization generally is performed in two steps. See,for example, U.S. Pat. Nos. Re. 26,065; 3,433,772; 3,509,108; 3,551,389;3,655,632; 4,312,976; 4,717,764; & 7,696,302 each is incorporated hereinby reference. The first step is the reaction of the monomers, and thesecond step increases the molecular weight of the polymer. The polymertypically requires an inherent viscosity (IV), measured in sulfuricacid, of greater than 0.4 dl/g (typically 0.50-1.20). This polymer, orresin, may be subsequently formed into, among other things, fibers andfilms. The process for forming fibers and films requires the productionof a dope (about 25% by weight polymer in solvent for fiber spinningoperations, about 15% for film casting operations, about 10% for handcasting of films), and extrusion of the dope into either the fiber orfilm with the evolution of the solvent. While this process has produceda PBI that has met with great commercial success, the cost of producingthe polymer has been limiting in the wide industrial acceptance of thepolymer.

Solution polymerization is also known, see Powers and Serad, mentionedabove, page 2. However, the solution polymerization method has beennothing more than an academic novelty. A significant problem is thatsolution polymerization has been conducted at low monomerconcentrations. Another problem is that as the monomer concentration inthe solution increases, the polymer's IV decreases. See for example,Mader, J. et al., Polybenzimidazole/Acid Complexes as High-TemperatureMembranes, Adv Polym Sci (2008) 216: 63-124, page 103, FIG. 14(reproduced here as FIG. 1). Because the solution method has notproduced polymer with a sufficiently high IV or a solution with asufficiently high solids content, this method has not been exploitedcommercially.

There is a need for a method of making a polybenzimidazole having asufficiently high IV and a high solids content in solution.

DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in thedrawings a form that is presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

FIG. 1 is a graph (Prior Art) showing that a monomer concentration, inthe solution, increases, the polymer's intrinsic viscosity (IV)decreases.

FIG. 2 is a schematic illustration of an embodiment of the instantinvention.

FIG. 3 is a graph showing polymer IV as a function of monomerconcentration in the solution (invention).

FIG. 4 is a schematic illustration of a synthesis of the adducts thatmay be used in the instant invention.

SUMMARY OF THE INVENTION

A method of making a polybenzimidazole (PBI) includes the steps of:reacting, in a solution, an organic compound having at least 2 aminogroups with an organic aldehyde adduct, the reactants comprise at least8% by weight of the solution. A solvent of the solution may be selectedfrom the group of: N,N-dimethylacetamide (DMAc), N,N-dimethylformamide(DMF), dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP),tetramethylene sulfone, and combinations thereof. The organic aldehydeadduct may be an organic aldehyde bisulfite adduct. The organic aldehydeportion of the organic aldehyde adduct being aliphatic, alicyclic,aromatic, heterocyclic, or heteroaromatic aldehyde or mixtures thereof.The polybenzimidazole may have an intrinsic viscosity of at least 0.40dl/g.

DESCRIPTION OF THE INVENTION

Polybenzimidazoles (PBI) are a known class of compounds. See, forexample, US Re26065; U.S. Pat. Nos. 3,433,772; 4,717,764; and 7,696,302,each of which is incorporated herein by reference. Examples ofpolybenzimidazoles include:poly-2,2′-(m-phenylene)-5,5′-bibenzimidazole;poly-2,2′-(biphenylene-2″2′″)-5,5′-bibenzimidazole;poly-2,2′-(biphenylene-4″4′″)-5,5′-bibenzimidazole;poly-2,2′-(1″,1″,3″trimethylindanylene)-3″5″-p-phenylene-5,5′-bibenzimidazole;2,2′-(m-phenylene)-5,5′-bibenzimidazole/2,2-(1″,1″,3″-trimethylindanylene)-5″,3″-(p-phenylene)-5,5′-bibenzimidazolecopolymer;2,2′-(m-phenylene)-5,5-bibenzimidazole-2,2′-biphenylene-2″,2′″-5,5′-bibenzimidazolecopolymer; poly-2,2′-(furylene-2″,5″)-5,5′-bibenzimidazole;poly-2,2′-(naphthalene-1″,6″)-5,5′-bibenzimidazole;poly-2,2′-(naphthalene-2″,6″)-5,5′-bibenzimidazole;poly-2,2′-amylene-5,5′-bibenzimidazole;poly-2,2′-octamethylene-5,5′-bibenzimidazole;poly-2,2′-(m-phenylene)-diimidazobenzene;poly-2,2′-cyclohexenyl-5,5′-bibenzimidazole;poly-2,2′-(m-phenylene)-5,5′-di(benzimidazole)ether;poly-2,2′-(m-phenylene)-5,5′-di(benzimidazole)sulfide;poly-2,2′-(m-phenylene)-5,5′-di(benzimidazole)sulfone;poly-2,2′-(m-phenylene)-5,5′-di(benzimidazole)methane;poly-2,2″-(m-phenylene)-5,5″-di(benzimidazole)propane-2,2; andpoly-ethylene-1,2-2,2″-(m-phenylene)-5,5″-dibenzimidazole)ethylene-1,2where the double bonds of the ethylene groups are intact in the finalpolymer. Poly-2,2′-(m-phenylene)-5,5′-bibenzimidazole is preferred.

FIG. 2 is a schematic illustration of the reaction of one embodiment ofthe instant invention. Generally, FIG. 2 illustrates an organic compound(A) reacted, in solution, with an adduct (B) to obtain a product (C).More specifically, FIG. 2 illustrates an organic compound having atleast 2 amino groups (A) reacted, in solution, with an organic aldehydeadduct (B) to obtain a polybenzimidiazole (C). In one embodiment, it maybe beneficial to add an excess of the salt used to form the adduct(discussed below) to the reaction mixture (this may be used as a measureto support conversion of any traces of free aldehyde to the adduct).

In general, the method (reaction) is a solution polymerization where thereactants (or monomers) comprise at least 8% by weight of the solution.Preferably, the reactants may comprise at least 10%, or at least 15%, orat least 20%, or at least 25%, or up to 40%, or in a range of 20-30%, orin a range of 20-35% by weight of the solution (and subsets thereof).

By such reaction, one obtains the surprising result that increasingsolids content in the polymerization yields increasing IVs. This isillustrated in FIG. 3. The resulting PBI may have an IV, measured insulfuric acid (method set out below), of at least 0.4 dl/g, or at least0.5 dl/g, or at least 0.7 dl/g, or at least 1.0 dl/g, or at least 1.20dl/g (and subsets thereof).

The reaction conditions may be at any pressure and any temperatures.Excessive pressures and temperatures are not necessary to advance thereaction. Temperatures may range from 100° C. to 285° C. In oneembodiment, the temperature is from 150° C. to 200° C., and the pressureis atmospheric.

The solvents for the solution polymerization may include any solvent forthe reactants and polymer. Solvents may include N,N-dimethylacetamide(DMAc), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO),N-methyl-2-pyrrolidone (NMP), tetramethylene sulfone, and combinationsthereof. In one embodiment, the solvent may be N,N-dimethylacetamide(DMAc).

The solvents may optionally contain a salt to help extend the shelf lifeof the solution. Such a salt may be lithium chloride, calcium chloride,and combinations thereof. The salt may be present in a range of up to10%. In one embodiment, the salt may be about 2-4% by weight of thesolution. In another embodiment, the salt may be lithium chloride atabout 2-4% by weight of the solution.

The reactants may be: 1) an organic compound having at least 2 aminogroups, preferably at least 4 amino groups, and most preferably 4 aminogroups; and 2) an organic aldehyde adduct.

The organic compound having the amino groups may be any organic compoundhaving the specified number of amino groups. Those organic compounds maybe selected from the group of aliphatic, alicyclic, aromatic,heterocyclic, or heteroaromatic compounds and mixtures thereof. Thearomatic and heteroaromatic tetra-amino compounds may include, forexample, 3,3′,4,4′-tetra-aminobiphenyl, 2,3,5,6-tetra-aminopyridine,1,2,4,5-tetra-aminobenzene, 3,3′,4,4′-tetra-aminodiphenylsulfone,3,3′,4,4′-tetra-aminodiphenyl ether, 3,3′,4,4′-tetra-aminobenzophenone,3,3′,4,4′-tetra-aminodiphenyl methane, and3,3′,4,4′-tetra-aminodiphenyldimethylmethane. In one embodiment, theorganic compound is tetraminobenzene. In a preferred embodiment, theorganic compound is a tetraamino biphenyl (TAB).

The organic aldehyde adduct may be any organic aldehyde adduct. In FIG.4, there is a schematic illustration of the production of two suchadducts. Generally, an aldehyde (A) reacts with a bisulfite (B) toobtain the organic aldehyde adduct (C). This reaction is conducted in anaqueous solution of alcohol (e.g., methanol) at a temperature in therange of about 20-40° C. for a period of about 2-24 hours. In oneembodiment, the organic aldehyde adduct is an organic aldehydebisulfite. Bisulfite salts used in making the organic aldehyde adductmay include metal salts such as sodium bisulfite or potassium bisulfite,sodium metabisulfite, potassium metabisulfite or non-metal salts such asammonium sulfite and ammonium metabisulfite. In another embodiment, theorganic aldehyde adduct is an organic aldehyde bis (bisulfite). Theorganic aldehyde portion of the organic aldehyde adduct may be anyorganic aldehyde. Those organic aldehydes may be selected from the groupof aliphatic, alicyclic, aromatic, heterocyclic, or heteroaromaticcompounds and mixtures thereof. In one embodiment, the organic aldehydeis terephthaldehyde. In another embodiment, the organic aldehyde isisophthalaldehyde.

Upon completion of the solution polymerization, the polymer may beremoved from the solvent for use in resin form (e.g., powder or pellets)or may be ready for extrusion into a form of, for example, a fiber or afilm.

For thermoplastic molding applications, the polymer should have an IV ofat least 0.40 dl/g upon isolation from solution, or in the range of0.40-0.60 dl/g, or in the range of 0.45-0.55 dl/g (and subsets thereof).For polymer in solution to be extruded as fiber, the IV should be atleast 0.50 dl/g, or 0.60-0.80 dl/g, and or 0.68-0.76 dl/g (and subsetsthereof). For fiber spinning, the polymer weight % solids in thesolution may be greater than 15%, or 20-35%, or 25-30% (and subsetsthereof). For film formation by any means, the polymer IV in solutionshould be at least 0.80 dl/g, or greater than 1.00 dl/g, or greater than1.10 dl/g (and subsets thereof). For film formation, the polymer weight% solids in solution may be at least 10%, or 14-25%, or 15-20% (andsubsets thereof).

Methods

The following methods are used throughout the instant application forreported values.

Inherent Viscosity (IV) Measurement Method

0.050 g polybenzimidazole is added to a 25 mL volumetric flask. Theflask is filled with concentrated sulfuric acid for a finalconcentration of 0.2 g/dL. The flask is shaken on a mechanical shakeruntil all polybenzimidazole is dissolved. The polybenzimidazole solutionis filtered through a 0.45 μm PTFE syringe filter and added to a 200 μmUbbelohde viscometer. The viscometer is placed into a 30.0° C. waterbath and allowed to equilibrate for 30 minutes. Measurements arerecorded until three consecutive times are within 0.1 seconds. Theaverage of these three times is used to calculate the inherent viscosityusing the following equation:

$\eta_{inh} = \frac{\ln \left( {t\text{/}t_{0}} \right)}{C}$

n_(inh) (dL/g): inherent viscosity (IV)t (sec): solution flow timet₀ (sec): solvent flow time (96% sulfuric acid)C (g/dL): solution concentration

Infrared Spectroscopy

Attenuated total reflectance (ATR) spectra were obtained using a PerkinElmer Spectrum 100 FT-IR with a three reflection diamond/ZnSe crystal.Spectroscopy was performed for the analysis of monomers and dry polymersamples in the range of 4000-650 cm⁻¹.

TGA Measurements

Thermogravimetric analysis (TGA) was performed on a TA Instruments Q5000TGA using 5-10 mg samples heated from 25° C. to 1,000° C. under anitrogen purge with a heating rate of 5° C./min.

EXAMPLES

In the following examples, when 2 wt % LiCl salt is mentioned, it refersto a premixed solution of DMAc with 2 wt % LiCl was used as the reactionsolvent.

Comparative Examples Low Polymer Solids Comparative Example 1

1.179 g tetraaminobiphenyl (TAB, 5.5 mmol), 1.883 g isophthalaldehydebisulfite adduct (IBA, 5.5 mmol) and 80 mL N,N-dimethylacetamide/lithiumchloride (2 wt %) (DMAc/LiCl, 2.2% calculated wt % polymerconcentration) were added to a three-neck 100 mL round bottom flask. Theflask was then equipped with a reflux condenser, stir-rod connected to amechanical overhead stirrer, and a nitrogen inlet/outlet. The reactantmixture was purged with nitrogen and placed in a silicone oil bath. Oilbath temperature was regulated by a thermal controller with programmableramp/soak features. The reaction mixture was heated to refluxtemperature (approximately 170° C.) and allowed to react for 24 hours.The resulting polymer solution was precipitated in de-ionized (DI) waterto isolate the polymer product. The polymer was then dried at 220° C.for 12 hours. Inherent viscosity (IV) measurements were conducted at aconcentration of 0.002 g/mL in concentrated sulfuric acid (H₂SO₄) andare an average of three measurements. IV=0.28 dug.

Comparative Example 2

1.179 g tetraaminobiphenyl (TAB, 5.5 mmol), 1.883 g isophthalaldehydebisulfite adduct (IBA, 5.5mmol) and 50 mL N,N-dimethylacetamide/lithiumchloride (2 wt %) (DMAc/LiCl, 3.5% calculated wt % polymerconcentration) were added to a three-neck 100 mL round bottom flask. Theflask was then equipped with a reflux condenser, stir-rod connected to amechanical overhead stirrer, and a nitrogen inlet/outlet. The reactantmixture was purged with nitrogen and placed in a silicone oil bath. Oilbath temperature was regulated by a thermal controller with programmableramp/soak features. The reaction mixture was heated to refluxtemperature (approximately 170° C.) and allowed to react for 24 hours.The resulting polymer solution was precipitated in de-ionized (DI) waterto isolate the polymer product. The polymer was then dried at 220° C.for 12 hours. Inherent viscosity (IV) measurements were conducted at aconcentration of 0.002 g/mL in concentrated sulfuric acid (H₂SO₄) andare an average of three measurements. IV=0.25 dug.

Adduct Preparation Examples Adduct Example 1 Isophthalaldehyde BisulfiteAdduct Preparation

208.43 g isophthalaldehyde (1.55 moles) and 3475 mL methanol were addedto a 5 L round bottom flask. The solution was stirred until allisophthalaldehyde was dissolved. In a separate flask, 332.30 g sodiumbisulfite (3.19 moles) and 525 mL water were mixed until all sodiumbisulfite was dissolved. The sodium bisulfite solution was addeddropwise over two hours to the isophthalaldehyde-methanol solution whilestirring. After stirring for 24 hours, the isophthalaldehyde bisulfiteadduct was filtered, washed with 2 L methanol, then dried at 60° C. in avacuum oven. NMR confirmed the isophthalaldehyde bisulfite adduct wasformed. Yields of several runs: 96-98%.

Adduct Example 2 Terephthaldehyde Bisulfite Adduct Preparation

10.00 g terephthalaldehyde (TPA, 74.6 mmol) and 350 ml methanol wereadded to a 500 ml round bottom flask, then mixed with an overheadstirrer. 15.54 g sodium bisulfite (NaBS, 149.2 mmol) was weighed out anddissolved in 24 ml deionized water in a separate flask. The TPA mixturewas heated to 35° C. for 30 minutes to aid in dissolution, then cooledto 30° C. before the dropwise addition of the NaBS solution via anaddition funnel. As the TPA adduct formed it precipitated from solution.The reaction was allowed to stir overnight before filtering the product.The TPA adduct was washed twice with 100 ml methanol before drying in avacuum oven overnight at 60° C. Yield: 24.05 g (94.8%).

Inventive Examples High Polymer Solids Inventive Example 1

2.504 g tetraaminobiphenyl (TAB, 11.7 mmol), 4.002 g isophthalaldehydebisulfite adduct (IBA, 11.7 mmol) and 23 mLN,N-dimethylacetamide/lithium chloride (2 wt %) (DMAc/LiCl, 14.3%calculated wt % polymer concentration) were added to a three-neck 100 mLround bottom flask. The flask was then equipped with a reflux condenser,stir-rod connected to a mechanical overhead stirrer, and a nitrogeninlet/outlet. The reactant mixture was purged with nitrogen and placedin a silicone oil bath. Oil bath temperature was regulated by a thermalcontroller with programmable ramp/soak features. The reaction mixturewas heated to reflux temperature (approximately 170° C.) and allowed toreact for 24 hours. The resulting polymer solution was precipitated inde-ionized (DI) water to isolate the polymer product. The polymer wasthen dried at 220° C. for 12 hours. Inherent viscosity (IV) measurementswere conducted at a concentration of 0.002 g/mL in concentrated sulfuricacid (H₂SO₄) and are an average of three measurements. IV=0.73 dL/g. IRspectrum was recorded and appeared identical to the spectrum recordedfrom a commercial PBI sample.

Inventive Example 2

2.504 g tetraaminobiphenyl (TAB, 11.7 mmol), 4 g isophthalaldehydebisulfite adduct (IBA, 11.7 mmol) and 17.4 mLN,N-dimethylacetamide/lithium chloride (2 wt %) (DMAc/LiCl, 18.1%calculated wt % polymer concentration) were added to a three-neck 100 mLround bottom flask. The flask was then equipped with a reflux condenser,stir-rod connected to a mechanical overhead stirrer, and a nitrogeninlet/outlet. The reactant mixture was purged with nitrogen and placedin a silicone oil bath. Oil bath temperature was regulated by a thermalcontroller with programmable ramp/soak features. The reaction mixturewas heated to reflux temperature (approximately 170° C.) and allowed toreact for 24 hours. The resulting polymer solution was precipitated inde-ionized (DI) water to isolate the polymer product. The polymer wasthen dried at 220° C. for 12 hours. Inherent viscosity (IV) measurementswere conducted at a concentration of 0.002 g/mL in concentrated sulfuricacid (H₂SO₄) and are an average of three measurements. IV=0.96 dL/g. IRand NMR spectra were recorded and appeared identical to the spectrarecorded from a commercial PBI sample.

Inventive Example 3

2.504 g tetraaminobiphenyl (TAB, 11.7 mmol), 4 g isophthalaldehydebisulfite adduct (IBA, 11.7 mmol) and 10.45 mLN,N-dimethylacetamide/lithium chloride (2 wt %) (DMAc/LiCl, 26.9%calculated wt % polymer concentration) were added to a three-neck 100 mLround bottom flask. The flask was then equipped with a reflux condenser,stir-rod connected to a mechanical overhead stirrer, and a nitrogeninlet/outlet. The reactant mixture was purged with nitrogen and placedin a silicone oil bath. Oil bath temperature was regulated by a thermalcontroller with programmable ramp/soak features. The reaction mixturewas heated to reflux temperature (approximately 170° C.) and allowed toreact for 16 hours. The resulting polymer solution solidified. Thepolymer was crushed and washed in de-ionized (DI) water and was thendried at 220° C. for 12 hours. Inherent viscosity (IV) measurements wereconducted at a concentration of 0.002 g/mL in concentrated sulfuric acid(H₂SO₄) and are an average of three measurements. IV=0.78 dL/g.

Inventive Example 4

2.504 g tetraaminobiphenyl (TAB, 11.7 mmol), 4 g isophthalaldehydebisulfite adduct (IBA, 11.7 mmol) and 17.8 mL N,N-dimethylacetamide(DMAc, 17.8% calculated wt % polymer concentration) were added to athree-neck 100 mL round bottom flask. The flask was then equipped with areflux condenser, stir-rod connected to a mechanical overhead stirrer,and a nitrogen inlet/outlet. The reactant mixture was purged withnitrogen and placed in a silicone oil bath. Oil bath temperature wasregulated by a thermal controller with programmable ramp/soak features.The reaction mixture was heated to reflux temperature (approximately170° C.) and allowed to react for 24 hours. The resulting polymersolution was precipitated in de-ionized (DI) water to isolate thepolymer product. The polymer was then dried at 220° C. for 12 hours.Inherent viscosity (IV) measurements were conducted at a concentrationof 0.002 g/mL in concentrated sulfuric acid (H₂SO₄) and are an averageof three measurements. IV=0.55 dug.

Inventive Example 5

2.504 g tetraaminobiphenyl (TAB, 11.7 mmol), 4 g isophthalaldehydebisulfite adduct (IBA, 11.7 mmol) and 16.2 mL N,N-dimethylacetamide(DMAc, 19.2% calculated wt % polymer concentration) were added to athree-neck 100 mL round bottom flask. The flask was then equipped with areflux condenser, stir-rod connected to a mechanical overhead stirrer,and a nitrogen inlet/outlet. The reactant mixture was purged withnitrogen and placed in a silicone oil bath. Oil bath temperature wasregulated by a thermal controller with programmable ramp/soak features.The reaction mixture was heated to reflux temperature (approximately170° C.) and allowed to react for 24 hours. The resulting polymersolution was precipitated in de-ionized (DI) water to isolate thepolymer product. The polymer was washed with methanol (MeOH) using aSoxhlet extractor for 24 hours. The product was then dried at 60° C. for12 hours. Inherent viscosity (IV) measurements were conducted at aconcentration of 0.002 g/mL in concentrated sulfuric acid (H₂SO₄) andare an average of three measurements. IV=1.03 dL/g.

Inventive Example 6

2.504 g tetraaminobiphenyl (TAB, 11.7 mmol), 4.006 g isophthalaldehydebisulfite adduct (IBA, 11.7 mmol) and 17.5 mL N,N-dimethylacetamide(DMAc, 18.0% calculated wt % polymer concentration) were added to athree-neck 100 mL round bottom flask. The flask was then equipped with areflux condenser, stir-rod connected to a mechanical overhead stirrer,and a nitrogen inlet/outlet. The reactant mixture was purged withnitrogen and placed in a silicone oil bath. Oil bath temperature wasregulated by a thermal controller with programmable ramp/soak features.The reaction mixture was heated to reflux temperature (approximately170° C.) and allowed to react for 24 hours. The resulting polymersolution was precipitated in de-ionized (DI) water to isolate thepolymer product. The polymer was then dried at 220° C. for 12 hours.Inherent viscosity (IV) measurements were conducted at a concentrationof 0.002 g/mL in concentrated sulfuric acid (H₂SO₄) and are an averageof three measurements. IV=0.79 dL/g.

Inventive Example 7

2.184 g tetraaminobiphenyl (TAB, 10.2 mmol), 3.488 g isophthalaldehydebisulfite adduct (IBA, 10.1 mmol) and 9.9 mL N,N-dimethylacetamide(DMAc, 25.1% calculated wt % polymer concentration) were added to athree-neck 100 mL round bottom flask. The flask was then equipped with areflux condenser, stir-rod connected to a mechanical overhead stirrer,and a nitrogen inlet/outlet. The reactant mixture was purged withnitrogen and placed in a silicone oil bath. Oil bath temperature wasregulated by a thermal controller with programmable ramp/soak features.The reaction mixture was heated to reflux temperature (approximately170° C.) and allowed to react for 24 hours. The resulting polymersolution was precipitated in de-ionized (DI) water to isolate thepolymer product. The polymer was then dried at 220° C. for 12 hours.Inherent viscosity (IV) measurements were conducted at a concentrationof 0.002 g/mL in concentrated sulfuric acid (H₂SO₄) and are an averageof three measurements. IV=0.45 dL/g.

Inventive Example 8

2.504 g tetraaminobiphenyl (TAB, 11.7 mmol), 4 g isophthalaldehydebisulfite adduct (IBA, 11.7 mmol) and 17.8 mL N,N-dimethylacetamide(DMAc, 17.8% calculated wt % polymer concentration) were added to athree-neck 100 mL round bottom flask. The flask was then equipped with areflux condenser, stir-rod connected to a mechanical overhead stirrer,and a nitrogen inlet/outlet. The reactant mixture was purged withnitrogen and placed in a silicone oil bath. Oil bath temperature wasregulated by a thermal controller with programmable ramp/soak features.The reaction mixture was heated to reflux temperature (approximately170° C.) and allowed to react for 18 hours. The resulting polymersolution was precipitated in de-ionized (DI) water to isolate thepolymer product. The polymer was then dried at 220° C. for 12 hours.Inherent viscosity (IV) measurements were conducted at a concentrationof 0.002 g/mL in concentrated sulfuric acid (H₂SO₄) and are an averageof three measurements. IV=0.6 dL/g.

Inventive Example 9 With Pre-Dissolved TAB Monomer

2.504 g tetraaminobiphenyl (TAB, 11.7 mmol) and 17.8 mL of DMAc wereadded to a 25 mL volumetric flask. The flask was placed on a mechanicalshaker until TAB monomer fully dissolved. Once dissolved, 3 hours wereallowed to pass to evaluate the solution stability. After 3 hours, thepremixed solution and 4 g isophthalaldehyde bisulfite adduct (IBA, 11.7mmol) were added to a three-neck 100 mL round bottom flask. The flaskwas then equipped with a reflux condenser, stir-rod connected to amechanical overhead stirrer, and a nitrogen inlet/outlet. The reactantmixture was purged with nitrogen and placed in a silicone oil bath. Oilbath temperature was regulated by a thermal controller with programmableramp/soak features. The reaction mixture was heated to refluxtemperature (approximately 170° C.) and allowed to react for 24 hours.The resulting polymer solution was precipitated in de-ionized (DI) waterto isolate the polymer product. The polymer was then dried at 220° C.for 12 hours. Inherent viscosity (IV) measurements were conducted at aconcentration of 0.002 g/mL in concentrated sulfuric acid (H₂SO₄) andare an average of three measurements. IV=0.90 dL/g.

Inventive Example 10 With Post Polymerization NaHSO₃ Addition forSolution Viscosity Modification

105.168 g tetraaminobiphenyl (TAB, 0.477 mol), 163 g isophthalaldehydebisulfite adduct (IBA, 0.477 mol) and 706 mL dimethylacetamide (DMAc,18.1% polymer solution) were added to a 1L three-neck reactor kettle.The kettle was then equipped with a reflux condenser, stir-rod connectedto a mechanical overhead stirrer, and a nitrogen inlet/outlet. Thereactant mixture was purged with nitrogen and placed in a silicone oilbath. Oil bath temperature was regulated by a thermal controller withprogrammable ramp/soak features. The reaction mixture was heated toreflux temperature (approximately 170° C.) and allowed to react for 24hours. An aliquot of the resulting polymer solution was precipitated inde-ionized (DI) water to isolate the polymer product. The polymer wasthen dried at 220° C. for 12 hours. Inherent viscosity (IV) measurementswere conducted at a concentration of 0.002 g/mL in concentrated sulfuricacid (H₂SO₄) and are an average of three measurements. IV=0.32 dL/g.

25.2 g of the polymer solution and 0.514 g NaHSO₃ were added to athree-neck reactor kettle. The reactor kettle was then equipped with astir shaft, and nitrogen inlet/outlet. The reaction kettle was purgedwith nitrogen, then heated to 140° C. and stirred at 40 RPM for 24hours. IV=0.4 dL/g. Solution Viscosity=3004.648 Poise

Inventive Example 11 With 2 wt % NaHSO₃ Added to Reaction Mixture Priorto Polymerization (2 wt % NaHSO₃ of Total Solution and Reactant Weights)

25.04 g tetraaminobiphenyl (TAB, 0.117 mol), 40 g isophthalaldehydebisulfite adduct (IBA, 0.117 mol), 4.58 g sodium bisulfite (NaHSO₃, 44mmol) and 175 mL N,N-dimethylacetamide (DMAc, 18.0% calculated wt %polymer concentration) were added to a 250 mL three-neck round bottomflask. The flask was then equipped with a reflux condenser, stir-rodconnected to a mechanical overhead stirrer, and a nitrogen inlet/outlet.The reactant mixture was purged with nitrogen and placed in a siliconeoil bath. Oil bath temperature was regulated by a thermal controllerwith programmable ramp/soak features. The reaction mixture was heated toreflux temperature (approximately 170° C.) and allowed to react for 24hours. An aliquot of the resulting polymer solution was precipitated inde-ionized (DI) water to isolate the polymer product. The polymer wasthen dried at 220° C. for 12 hours. Inherent viscosity (IV) measurementswere conducted at a concentration of 0.002 g/mL in concentrated sulfuricacid (H₂SO₄) and are an average of three measurements. IV=0.624 dL/g.

Inventive Example 12

2.504 g tetraaminobiphenyl (TAB, 11.7 mmol), 4.00 g isophthalaldehydebisulfite adduct (IBA, 11.8 mmol), and 17.5 ml N,N-dimethylacetamide(DMAc, 18.0 calculated wt % polymer concentration) were added to a 100ml resin kettle, mixed with an overhead stirrer, purged with drynitrogen. The mixture was heated to 140° C. for 24 hours. The inherentviscosity (IV) was 0.82 dL/g, as determined from a 0.002 g/mL solutionof polymer in concentrated H₂SO₄ at 30° C. Thermogravimetric analysisshowed that the thermal stability of the polymer as measured by the 5%weight loss of the original sample weight (after water removal) wasgreater than 550° C. The IR spectrum was recorded and appeared identicalto the spectrum recorded from a commercial PBI sample.

Inventive Example 13 22% Solids Polymerization with 2% Molar ExcessNaHSO₃

43.70 g isophthalaldehyde bisulfite adduct (IBA, 0.1277 moles), 27.36 gtetraaminobiphenyl (TAB, 0.1277 moles), 0.267 g sodium bisulfite(NaHSO₃, 0.0025 moles), and 150 mL N,N-dimethylacetamide (DMAc, 21.9%calculated wt % polymer concentration) was added to a 300 mL three-neckround bottom flask. The flask was fitted with a reflux condenser,overhead stirrer, and purged with dry nitrogen. The solution was heatedto reflux temperature (168° C.) and stirred at 30 RPM for 24 hours.Inherent viscosity of the polymer is 0.64 dL/g, as measured using a0.002 g/mL solution of polymer in concentrated sulfuric acid. The FTIRspectrum of the polymer appeared identical to the spectrum of acommercial PBI sample.

Inventive Example 14 22% Solids Polymerization with 4% Molar ExcessNaHSO₃

43.70 g isophthalaldehyde bisulfite adduct (IBA, 0.1277 moles), 27.36 gtetraaminobiphenyl (TAB, 0.1277 moles), 0.534 g sodium bisulfite(NaHSO₃, 0.0051 moles), and 150 mL N,N-dimethylacetamide (DMAc, 21.8%calculated wt % polymer concentration) was added to a 300 mL three-neckround bottom flask. The flask was fitted with a reflux condenser,overhead stirrer, and purged with dry nitrogen. The solution was heatedto reflux temperature (168° C.) and stirred at 30 RPM for 24 hours.Inherent viscosity of the polymer was 0.75 dL/g, as measured using a0.002 g/mL solution of polymer in concentrated sulfuric acid. The FTIRspectrum of polymer appeared identical to the spectrum of a commercialPBI sample.

Inventive Example 15 Copolymer, meta-r-para-PBI 1:1

2.504 g tetraaminobiphenyl (TAB, 11.7 mmol), 2.00 g isophthalaldehydebisulfite adduct (IBA, 5.9 mmol), 2.00 g terephthalaldehyde bisulfiteadduct (IBA, 5.9 mmol), and 17.5 ml N,N-dimethylacetamide (DMAc, 18.0%calculated wt % polymer concentration) were added to a 100 ml resinkettle, mixed with an overhead stirrer, and purged with dry nitrogen.The mixture was heated to reflux for 24 hours. The inherent viscosity(IV) was 0.495 dL/g, as determined from a 0.002 g/mL solution of polymerin concentrated H₂SO₄ at 30° C.

Inventive Example 16 Homopolymer of para-PBI

2.504 g tetraaminobiphenyl (TAB, 11.7 mmol), 4.00 g terephthalaldehydebisulfite adduct (IBA, 11.8 mmol), and 22.5 ml N,N-dimethylacetamide(DMAc, 14.6% calculated wt % polymer concentration) were added to a 100ml resin kettle, mixed with an overhead stirrer, and purged with drynitrogen. The mixture was heated to reflux for 24 hours. The inherentviscosity (IV) was 0.555 dL/g, as determined from a 0.002 g/mL solutionof the polymer in concentrated H₂SO₄ at 30° C.

The present invention may be embodied in other forms without departingfrom the spirit and the essential attributes thereof, and, accordingly,reference should be made to the appended claims, rather than to theforegoing specification, as indicated the scope of the invention.

We claim:
 1. A method of making a polybenzimidazole comprising the stepsof: reacting, in a solution, an organic compound having at least 4 aminogroups with an organic dialdehyde adduct, the reactants comprise atleast 8% by weight of the solution.
 2. The method of claim 1 where asolvent of the solution being selected from the group consisting of:N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF),dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), tetramethylenesulfone, and combinations thereof.
 3. The method of claim 1 wherein theorganic dialdehyde adduct being an organic dialdehyde bis (bisulfite)adduct.
 4. The method of claim 3 wherein the bisulfite portion of theorganic aldehyde bisulfite adduct being a bisulfite salt.
 5. The methodof claim 1 wherein the organic aldehyde portion of the organic aldehydeadduct is aliphatic, alicyclic, aromatic, heterocyclic dialdehyde ormixtures thereof.
 6. The method of claim 1 wherein the organic aldehydeportion of the organic aldehyde adduct is terephthalaldehyde orisophthalaldehyde.
 7. The method of claim 1 wherein the organic compoundbeing an organic tetraamine.
 8. The method of claim 1 further comprisingthe step of: extruding the polybenzimidazole to a fiber or a film fromthe solution.
 9. The method of claim 8 wherein for fiber spinning, thepolybenzimidazole having an intrinsic viscosity of at least 0.50 dl/g.10. The method of claim 8 wherein for fiber spinning, the solutionhaving a % solids of the solution of at least 15%.
 11. The method ofclaim 1 further comprising the step of: isolating the polybenzimidazolefrom the solvent.
 12. A method of making a polybenzimidazole comprisingthe steps of: reacting, in a solution, an organic compound having atleast 4 amino groups with an organic aldehyde adduct, the organicaldehyde adduct is a bisulfite salt.
 13. The method of claim 12 whereinthe reactants comprise at least 8% by weight of the solution.
 14. Themethod of claim 12 where a solvent of the solution being selected fromthe group consisting of: N,N-dimethylacetamide (DMAc),N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO),N-methyl-2-pyrrolidone (NMP), tetramethylene sulfone, and combinationsthereof.